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1. Field of the Invention
The present invention relates to an internal combustion engine which provides improved thermal efficiency.
2. Description of Prior Art
A modern internal combustion engine has a high performance of output power. Volumetric efficiency is one of the most important elements of the performance. The modern internal combustion engine has such unique valve overlap and timing to increase the volumetric efficiency as described by Crouse, Automotive Engines, Eighth Edition, 1995, pp 102. The modern engine takes the following an inlet-valve and outlet-valve operation:
1) The inlet-valve starts to open before an upper dead point of a piston and starts to close after a lower dead point of the piston in an intake-stroke.
2) The outlet-valve starts to open before the lower dead point and starts to close after the upper dead point of the piston in an exhaust stroke.
However, in view of thermal efficiency the modern combustion engine still needs improvements. It is the reason why there is always an appreciable loss (in the modern engine) due to the fact that the exhaust valve starts to open at a point before bottom center as described by Taylor, The Internal Combustion Engine in Theory and Practice, Volume 1: Thermodynamics, Fluid Flow, Performance, Second Edition 1985, pp 114.
To solve this problem the invented engine has an offset-cylinder and the closest structure of my invention is claim 1 of U.S. Pat. No. 1,956,804 which is patented on May 1, 1934 to A. J. Meyer.
However, neither valve nor means of valve overlap and timing are described in his claim 1. His claim 2 relates to opposed tendency of a piston to slap, but it does not relate to thermal efficiency. His claim 3 refers to detailed alignment of cylinders. His claim 4 describes the structure of sleeve valve type engine with offset-cylinder. His claim 5 describes opposed tendency for the pistons to slap against sleeve valve means.
Claims in Patent of Meyer does not refer to poppet-valve overlap and timing means which is one of the most important elements of the modern combustion engine.
My research is focused on improvement of the modern engine caused by the poppet-valve overlap and timing, and especially on reduction of exhaust loss cased by the open timing of the outlet-valve of the modern engine.
Combining the modern combustion engine which has poppet-valve overlap and timing means with old prior art structure (U.S. Pat. No. 1,956,804), the invented engine has an offset cylinder to counter direction of a crankshaft rotation. The invented engine ends a power stroke faster or a piston moves faster in the power stroke, then reduces exhaust loss caused by the outlet-valve open timing and improves the thermal efficiency. For the exact calculation of the torque of the invented engine, theoretical formulae are developed and it is further found that the invented engine increases torque and volumetric efficiency, and reduces heat loss, detonation and time loss. The reduction of the detonation of the invented engine enables the more advanced spark timing approximately from 0 to 5 degrees than the prior art of the modern engine. Thereby, the invented engine totally improves the thermal efficiency.